This application make reference to, incorporates the same herein, and claims all benefits acruing under 35 U.S.C xc2xa7119 from an application entitled A DISPLAY APPARATUS HAVING SELF-DIAGNOSTIC FUNCTION earlier filed in the Korean Industrial Property Office on 22 Oct. 1994 and assigned Ser. No. 27039/1994.
The present invention relates to an apparatus for a video display, and a more particularly, to a video display apparatus having a self-diagnostic circuit and method of implementing self-diagnosis by utilizing the same.
Conventionally, in a video display apparatus such as a monitor for a personal computer system, there is provided a raster arrangement for preventing a user from mistakenly believing a monitor is not operating properly when no raster pattern is displayed on the monitor""s screen when no video signal is input during a power-on state. An exemplary apparatus including such arrangement is disclosed in Korean Utility Model Application No, 85-4679, wherein a vertical oscillation signal of sawtooth wave shape is automatically displayed on the screen of a monitor when an input signal supplied to the monitor is shut off.
In the arrangement of such a conventional type display apparatus however, a raster signal for displaying a raster pattern is limited to only utilizing either a flyback pulse or a RC oscillation circuit, for example, such as one of a bridge type or of a shifted-phase type, thereby displaying a single image pattern on a screen. A synchronizing signal employed in the apparatus for displaying an image signal on the screen causes a vibration phenomenon when displaying video text, thereby resulting in an incorrect frequency adjustment for the synchronizing signal, for example, an error of approximately 1 KHz for a horizontal synchronizing signal and of approximately more than 3 Hz for a vertical synchronizing signal.
In addition, by only displaying a vertical signal of sawtooth wave type as a self raster signal during a period of no signal input, the above described apparatus merely provides the displayed sawtooth wave as a warning sign indicative of no video input signal to an observer.
Accordingly, it is an object of the present invention to provide a video display apparatus capable of self-diagnosis and a method therefore.
It is another object of the present invention to provide a self-diagnostic arrangement for a video display and method of implementing the same wherein an input external video signal is automatically detected in order to display a pictorial image on a screen in either the state the input video signal has been disabled or the state where the video display has disconnected from an external computer system, such that a variety of images are provided and displayed in order for an observer to confirm whether the monitor is in proper working order.
It is still another object of the present invention to provide a self-diagnosis arrangement for a video display and method thereof wherein a pictorial image in a more stabilized state is able to be displayed on a screen by use of an internally generated viable synchronizing signal when an external video signal input has been disabled.
It is yet another object of the present invention to provide a video display apparatus having a self-diagnostic function, which apparatus is capable of self-diagnosis, without using any external instruments for the diagnosis, during the process of production or when in use.
To achieve those and other objects, there is provided a video display apparatus including a cable connector which is connected to a signal cable extended from an external system, an amplifying portion for receiving and amplifying a video signal supplied from an external system via the cable connector, and a cathode ray tube for displaying a video signal input from the amplifying portion, which apparatus comprises a microprocessor for storing information on the details of the status of a display, for generating internal horizontal and vertical synchronizing signals, respectively of predetermined frequencies, by selectively switching between horizontal and vertical synchronizing signals supplied from either an internal generator or external system via the cable connector, a portion for supplying a blanking signal and an image data to the amplifying means for self-diagnosis correspondingly depending upon information provided from the microprocessor, and a horizontal/vertical deflection circuit for receiving the internal horizontal and vertical synchronizing signals from the microprocessor and for supplying horizontal and vertical synchronizing signals to the cathode ray tube.
The video display apparatus further incorporates an oscillator together with the microprocessor""s horizontal and vertical synchronizing circuit for generating internal horizontal and vertical synchronizing signals, and a pair of switches for switching between horizontal and vertical synchronizing signals internally generated or externally supplied for output to deflection circuitry of a cathode ray tube.
There is also provided a video display apparatus incorporating a microprocessor, an on screen display portion and a cathode ray tube, which is characterized in that an external video image signal input is detected to generate variable horizontal/vertical deflection frequencies using an internal clock signal generator so that, in the absence of the external signal input, a sustained stabilized image is displayed.
There is yet provided a video display apparatus wherein a variety of information is stored in an on-screen display integrated circuit to be displayed in the form of characters and patterns, thereby providing a viewer with detailed optional information.
To achieve the above objects of the present invention, there is provided a method for self-diagnosis comprising the steps of determining whether a signal cable is connected to a cable connector, generating internal horizontal and vertical synchronizing signals when no connection between the signal cable and the cable connector is detected, displaying an initial self-diagnostic function menu table, demanding an input by a key stroke manipulation from an user, and displaying a detail of a self-diagnostic information display in dependence upon the key input.